Unfortunately my MacBook Air does not have any USB cable connection I don't believe. My Cobalt does. Not sure if you can get something to connect to the Cobalt USB to then connect to the port I have to charge my MacBook.Great! You'll appreciate this if you start adding photos to dives.
As for your Cobalt, does it have a USB cable to connect to your Mac? You could always sync it with MacDive on the Mac and they'll sync over to the iPhone, just as you did the opposite way with the Teric. Because of iCloud syncing, it will all stay in sync. The one thing is that syncing the Cobalt's dives might mess with the dive numbers. You can fix that.
MacDive Help - Numbering Dives